Say again?
What is
loudness? Loudness is making a lot of
noise these days, but what does
it really mean?
by MC Patel, CEO, Emotion Systems
T here is certainly no shortage
of gurus who are happy to
posit answers, but are they
addressing the right questions?
For instance, much has been made of
the EBU’s recent Loudness Metering
specification (EBU Tech 3341). But
it has to be said that the EBU only
makes recommendations, not policy,
and a great deal of confusion remains.
Furthermore, every broadcaster sets
slightly different measurement settings,
so how - in the end - do customers
know what to measure to and what to
correct to?
It also seems to me that most
loudness “solutions” appear to reside
in the hardware domain whereas the
overwhelming industry drive is toward
file-based workflow and processing.
What’s really going on here? Let’s start
by defining loudness measurement.
What is loudness measurement?
Loudness measurement is determined
using a mathematical model of human
hearing to determine how “loud” an
audio sample is to listeners. Due to
the nature of sound and a whole
host of factors that affect the human
hearing mechanism, the sounds we
hear can often be very different from
the sounds actually emitted by a
speaker. Human hearing works in a
logarithmic manner, as modelled by the
decibel scale, with higher sensitivity in
the middle range, which means that
certain frequency sounds can appear
58 | TV-BAY MAGAZINE
comparatively louder even
though they are actually emitted
at the same decibel level as other
frequencies. Why does the industry need
tools to measure loudness?
Well, in the case of the CALM
Act in the US, heavy fines are a
pretty compelling incentive to get
loudness parameters right. In the
recent past, television sound was not
regarded as particularly important,
but that has obviously changed
dramatically in recent years. Many
TV and radio listeners are now quick
to complain when they perceive that
some programmes are occasionally
“too loud”. Sometimes this is merely a
subjective, individual response, but it is
now recognised as something that can
provoke genuine annoyance and deter
listeners and, hence, erode audience
figures. In what environments should
loudness measurement tools be
included? Initially, loudness or excessive variations
in loudness were regarded as an
issue for playout and in recent years
some hardware solutions to manage
loudness have been deployed in
transmission suits. At the same time,
others have recognised that potential
problems should not be left solely to
transmission operators and some post
production facilities have found that
broadcasters prefer programmes to
be delivered with loudness control or
normalisation already applied.
Loudness regulation and normalisation
has applications in a wide variety of
areas including broadcast playout,
archive digitisation and within post
production facilities. Generally
speaking, loudness control is also
becoming an issue for all media
organisations including, for instance,
clip libraries that will be increasingly
required to fix the inevitable variations in
audio levels on legacy tape and film content
as an added value to their customers.
What should a loudness
tool actually do?
A loudness tool should analyse audio files
and, preferably, automatically attenuate
and/or normalise the audio levels contained
within them to current standards. It should
be easy to use and not tie up expensive
resources or compromise audio quality.
How should those tools work?
The loudness algorithm introduced in
ITU BS.1770 models human hearing and
takes into account various factors such as
frequency weighting and dynamic range.
Existing loudness meters operate in an
analogue fashion similar to a PPM to give
an indication of loudness in one of several
units, depending on the weighting applied.
With the move to file based systems,
digital meters have been adopted that
are governed by regulations set out by
international broadcast bodies such as the
ITU or EBU. However, meters of this kind
do not give an overall view of the sample,
making quick, effective analysis difficult.
The introduction of “eFF”
We designed eFF from the ground up to
specifically tackle the need to address
increasingly diverse file-based content
sources. eFF’s highly modular design
means that it has an ever-increasing
inventory of functions and file types that
adapt to the changing needs of the
industry. Its focus on an organic automation
function from inception enables eFF to
integrate fully with existing Media Asset
Management systems, or be used as a
stand-alone loudness compliance system.
eFF requires only very basic training to use
and is designed to make it easy for non-
expert operators to achieve consistent and
accurate results. Operators can set up file
analysis parameters either from the GUI
or by using one of many programmable
profiles that can be tailored and stored for a
particular client.
Because it is file based, eFF is considerably
faster than real-time, and because audio
tracks can be analysed and fixed without
decoding the video transport wrapper the
process is highly efficient.
So, eFF is quick, accurate and easy, and
has already been installed at prestigious
London-based firms such as The
Mill, Smoke and Mirrors, Munky, and
Technicolor Network Services UK - and we
think that’s something to shout about.